KR200355645Y1 - up-converter for digital television signal - Google Patents

Abstract

The present invention relates to an upconverter for television signal processing that is suitable for preventing errors in digital data when processing digital signals.

A 44 MHz digital IF television signal is mixed with a 982 MHz local oscillation signal through a first frequency converter through an input filter, converted into a 1026 MHz intermediate frequency signal, and then output through a filter. In the up-converter for TV signal processing of a double conversion system that converts and outputs a signal of 57 to 861 MHz by mixing with a local oscillation signal of 1083 to 1887 MHz via 40).

The second frequency converter 40 includes a local oscillator 430 for generating a 1083-1887 MHz signal, a local oscillation signal amplifier 44 for amplifying a 1083-1887 MHz signal of the local oscillator 430, and The intermediate frequency signal amplifying unit 41 which amplifies the intermediate frequency signal of 1026 MHz, the signal of the local oscillation signal amplifying unit 430 and the signal of the intermediate frequency signal amplifying unit 41 are subtracted and mixed to obtain a 57 to 861 MHz signal. Mixing unit 42 for outputting a conventional configuration, wherein at least the intermediate frequency signal amplifier 41, the local oscillator 430, the local oscillation signal amplifier of the configuration of the second frequency converter 40 The 44 and the mixing unit 42 are integrated into the MMIC 40, and the local oscillating unit 430 is configured separately from an analog circuit to form a circuit connection with the MMIC 40.

Description

Up-converter for digital television signal

The present invention relates to an upconverter for television signal processing, and more particularly, to an upconverter for television signal processing that prevents errors in digital data to be suitable for processing digital signals.

Bondi television signals are generally generated as intermediate frequency (IF) signals of approximately 45 MHz frequency in the frequency spectrum. In order for a television signal to be broadcast on either airwaves or cable networks and to be used in standard television, the television signal must be converted to a higher frequency signal in the very high frequency (VHF) band or the ultra-high frequency (UHF) band.

This conversion is accomplished by a device known as an upconverter. The upconverter is installed in the radio relay station which is the origin of the television signal. The upconverter takes the IF television signal and converts it to a VHF or UHF signal to provide the converted signal for broadcast.

There are two types of upconverters, single conversion type and double conversion type.

The single conversion type converts the frequency between the input frequency and the output frequency at one time, and the double conversion type converts the input frequency into the first intermediate frequency and finally outputs the output frequency. Belongs.

The television signal processed by the up-converter is an analog signal. The analog television signal is transmitted based on a carrier wave of a specific frequency and modulates a change in the amplitude of the carrier according to the information of the television program. The television receiver demodulates the information of the television program in response to the modulation. It will be acquired and broadcast on television.

Recently, however, the above-described analog television signal has been developed to replace the digital television signal. Digital signals can carry a significant amount of information faster and, as a result, significantly improve the quality of the generated picture and sound provided to digital television receivers.

The problem with the move to the digital format for television signal broadcasting is that data errors of digital signals occur with existing analog upconverter equipment.

In the case of the double conversion method, the digital up-converter equipment uses the input filter 10 to input a digital IF television signal of 44 MHz (41.25 to 45.75 MHz in the case of an analog signal) including an audio signal component and a video signal component. Bandpass filter 31, amplifier 32, and band after mixing with local oscillation signal of 982MHz by converting into intermediate frequency signal of 1026MHz (1027.75MHz for analog signal) while passing through first frequency converter 2 through Output through the pass filter 33, and the output is mixed with a local oscillation signal of 1083 ~ 1887MHz via the second frequency converter 40, and converted to a signal of 57 ~ 861MHz (50 ~ 860MHz for analog signals) This is finally output via the manual gain adjustment circuit 51 and the band pass filter 52.

In the case of the existing analog upconverter equipment, a local oscillator (Local OSC) 23,43, a mixer (22, 42), an amplification circuit, which constitute the first and second frequency converters (2, 4). (amp; 21, 41, 24, 44) were integrated into a microwave monolitic intergrated circuit (chip model name ACU2109).

When the analog upconverter of this structure is used as it is for digital signal processing, the output VHF or UHF signal is converted into a television receiver, even though the difference between the analog television signal and the digital television signal varies only in the frequency of the input and output signals. There has been a problem in that digital data, which is difficult to reproduce, is broken.

The present inventors have estimated that such a problem is caused by phase noise as a result of circuit analysis at each point.In order to solve the phase noise as a technical problem and to achieve such technical problem, integrated and analog circuits for each component circuit are achieved. As a result of experimenting while constructing, the following configuration has provided an upconverter for television signal processing that solves the conventional problems.

1 is a circuit block diagram illustrating a general upconverter concept.

2 is a circuit block diagram illustrating a concept according to the present invention.

Explanation of symbols on the main parts of the drawings

10-input filter 20-first frequency converter

21-Input signal amplifier 22-Mixer

24-Local Oscillator 31,33-Band Pass Filter

32-amplifier 40-second frequency converter

41-Intermediate Frequency Signal Amplifier 42-Mixer

44-Local Oscillation Signal Amplifier 51-Passive Gain Control Circuit

52-Bandpass Filter 230-Local Oscillator

430-Local Oscillator

The present invention for achieving the above-described technical problem is described with reference to the accompanying Figure 2 as follows.

The upconverter of the double conversion method for digital television signal processing of the present invention,

A 44 MHz digital IF television signal including an audio signal component and a video signal component is mixed with a 982 MHz local oscillation signal through a first frequency converter 20 through an input filter 10 and converted into a 1026 MHz intermediate frequency signal. After outputting through the band pass filter 31, the amplifier 32 and the band pass filter 33, the output is mixed with a local oscillation signal of 1083-1887 MHz while passing through the second frequency converter 40. In the up-converter for the television signal processing of the double conversion system which converts into a signal of 861 MHz and finally outputs it through the manual gain adjustment circuit 51 and the band pass filter 52,

The second frequency converter 40 includes a local oscillator 430 for generating a 1083-1887 MHz signal, a local oscillation signal amplifier 44 for amplifying a 1083-1887 MHz signal of the local oscillator 430, and The intermediate frequency signal amplifying unit 41 which amplifies the intermediate frequency signal of 1026 MHz, the signal of the local oscillation signal amplifying unit 430 and the signal of the intermediate frequency signal amplifying unit 41 are subtracted and mixed to obtain a 57 to 861 MHz signal. It is a typical configuration consisting of a mixing unit 42 for outputting,

At least the intermediate frequency signal amplifying unit 41, the local oscillating unit 430, the local oscillating signal amplifying unit 44, and the mixing unit 42 of the configuration of the second frequency converting unit 40 to the MMIC 40. Integrated configuration, the local oscillator 430 is characterized in that the circuit configuration is configured separately from the analog circuit by configuring the MMIC (40).

In this case, the MMIC 40 may or may not have an integrated local oscillation unit therein. That is, a conventional MMIC may be manufactured without a local oscillation unit integrated in the MMIC 40, and another conventional MMIC having a local oscillation unit may be used as it is, but without using a local oscillation unit existing inside the MMIC. As described above, the local oscillator 430 configured by the analog circuit may be connected to the related pin of the MMIC 40.

The local oscillator 430 is connected to a conventional phase locked loop (PLL) 45. The PLL 45 may be configured together in the MMIC 40 or may be implemented as a separate integrated device externally.

In the configuration of the first frequency converter 20, a local oscillator 230 for generating a 982 MHz signal is separately configured by an analog circuit, and a local oscillation signal amplifier 24 for amplifying the 982 MHz signal and the 44 MHz input. The input signal amplifier 21 which amplifies the signal, and the mixing unit 22 which adds and mixes the signal of the local oscillation amplifier 24 and the signal of the input signal amplifier 21 to output a 1026 MHz signal are MMIC. It is preferable to configure the integrated circuit.

However, according to the experiment results of the present inventors, even if the local oscillator 230 is integrated in the MMIC 20 in the case of the first frequency converter 20, the quality of the 57 to 861 MHz output signal is not a big problem. In the case of the second frequency converter 40, it was confirmed that the local oscillator 430 must be configured as an analog circuit separate from the MMIC 40.

The local oscillator 430 of the first frequency converter 40 is configured as follows.

In order to match the PLL circuit 45 with the filter constant for tuning the channel, RLC combines the bypass capacitor C1, the resistor R1, and the coil L1 in the form of a T, and at the rear of the coil L1 through the capacitor C6 to the base of the transistor Q1. The capacitor C2 and the variable-capacitance diode D1 are connected in series and grounded, and the capacitor C3 and the dielectric resonator RO1 are connected in series with the base of the transistor Q1 to ground, and a bias voltage is applied through the resistor R4. The capacitor C7 for coupling the bypass capacitor C4 and the bias resistor R2 to the emitter of the transistor Q1 and grounding is coupled to the emitter of the level attenuation resistor R3 and the local oscillation signal amplifier 44. It may be connected in series. The transistor Q1, the capacitors C2, C3 and C3 and the dielectric resonator R01 form a resonant circuit for resonating a desired band frequency by a combination of each other.

This configuration of the resonant circuit can increase the initial start wavelength, and can subsequently increase the local oscillation signal continuously oscillating.

When the local oscillator 230 of the first frequency converter is configured of an analog circuit, the local oscillator 430 of the first frequency converter is configured to be identical to the local oscillator 430 of the second frequency converter.

Among the components of the local oscillators 430 and 230, the dielectric resonator RO1 constituting the resonant circuit for resonating the band frequency generally adopts a dielectric resonator known to have excellent reactance characteristics.

The capacitors constituting the circuit of the local oscillation unit 430 are preferably configured using a ceramic capacitor having excellent capacitance characteristics.

When the local oscillation parts 430 and 230 are configured as an analog circuit, an inductor (called L) manufactured by forming a micro strip line on a wafer substrate and a capacitor (C) formed by forming two electrodes with an oxide film interposed therebetween. Compared to the up-converter using the conventional MMIC equipped with a high-capacity individual element LC, which has a large capacitance value and excellent device characteristics, the peak resonance Q value of the first oscillation for local oscillation can be used. The phase noise characteristics of the continuously oscillating signal can be improved as compared with the time of use, and accordingly, the 57-861 MHz signal and the subtracted and mixed by the mixing section 42 of the second frequency converter 40 are outputted. The quality of the digital data carried on the signal is good.

As described above, the present invention can increase the LC value of the local oscillation part as compared with the integrated MMIC, and can adopt an element having a small error due to the characteristics of individual elements, thereby increasing the initial resonance Q value for the oscillation of the local oscillation part. Therefore, the phase noise characteristic of the oscillation signal is improved, thereby generating a reliable carrier frequency signal that does not break the digital data, thereby providing an upconverter suitable for television digital signal broadcasting.

Claims (3)

A 44 MHz digital IF television signal including an audio signal component and a video signal component is mixed with a 982 MHz local oscillation signal through a first frequency converter 20 through an input filter 10 and converted into a 1026 MHz intermediate frequency signal. After outputting through the band pass filter 31, the amplifier 32 and the band pass filter 33, the output is mixed with a local oscillation signal of 1083-1887 MHz while passing through the second frequency converter 40. In the up-converter for the television signal processing of the double conversion system which converts into a signal of 861 MHz and finally outputs it through the manual gain adjustment circuit 51 and the band pass filter 52, The second frequency converter 40 includes a local oscillator 430 for generating a 1083-1887 MHz signal, a local oscillation signal amplifier 44 for amplifying a 1083-1887 MHz signal of the local oscillator 430, and The intermediate frequency signal amplifying unit 41 which amplifies the intermediate frequency signal of 1026 MHz, the signal of the local oscillation signal amplifying unit 430 and the signal of the intermediate frequency signal amplifying unit 41 are subtracted and mixed to obtain a 57 to 861 MHz signal. It is a typical configuration consisting of a mixing unit 42 for outputting, At least the intermediate frequency signal amplifying unit 41, the local oscillating signal amplifying unit 44, and the mixing unit 42 of the second frequency converting unit 40 may be integrated into the MMIC 40. The oscillator 430 is configured as an analog circuit separately configured to connect the circuit with the MMIC (40) up-converter for television signal processing. The local oscillation signal amplifying unit 24 according to claim 1, further comprising a local oscillator 230 for generating a 982 MHz signal in an analog circuit and amplifying the 982 MHz signal in the first frequency converter 20. ), An input signal amplifier 21 for amplifying the 44 MHz input signal, a mixed signal of the local oscillator amplifier 24 and the signal of the input signal amplifier 21, and outputting a 1026 MHz signal. An up-converter for television signal processing comprising a unit 22 integrated with an MMIC. The local oscillator (430) (230) according to any one of the preceding claims, wherein the local oscillator (430) (230), respectively, the bypass capacitor (C1), resistor (R1) and coil (L1) in the form of T to match the filter constant for tuning the PLL circuit and the channel. RLC is coupled, and the rear end of the coil L1 is connected to the base of the transistor Q1 through the capacitor C6, and branched to connect the capacitor C2 and the variable capacitor diode D1 in series, and ground the capacitor C3 and the dielectric to the base of the transistor Q1. The resonator RO1 is connected in series and grounded, and a bias voltage is applied through the resistor R4. The bypass capacitor C4 and the bias resistor R2 are connected and grounded to the emitter of the transistor Q1. A television signal processing device characterized in that the resistor R3 and a capacitor C7 for coupling to the local oscillation signal amplifying unit are connected in series. Butter.